Move compositor InputHandler from RenderViewImpl to RenderWidget.

At present the input handler for cross-process iframes is installed
only on the RenderViewImpl, meaning that events sent to them can only
be handled on the main thread (instead of the compositor thread).

Note: The compositor layer tree on the RenderViewImpl for a cross-
process frame renderer is actually empty.

This CL attaches an input handler to each RenderWidget instead,
allowing compositor-thread handling of input events for all
the frames. This is a precursor for handling GesturePinch events for
subframes.

[email protected]
BUG=654917
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2479663002
Cr-Commit-Position: refs/heads/master@{#445295}
diff --git a/content/renderer/render_thread_impl.h b/content/renderer/render_thread_impl.h
index ff541333..1506ecf 100644
--- a/content/renderer/render_thread_impl.h
+++ b/content/renderer/render_thread_impl.h
@@ -236,6 +236,7 @@
   cc::TaskGraphRunner* GetTaskGraphRunner() override;
   bool AreImageDecodeTasksEnabled() override;
   bool IsThreadedAnimationEnabled() override;
+  bool IsScrollAnimatorEnabled() override;
 
   // blink::scheduler::RendererScheduler::RAILModeObserver implementation.
   void OnRAILModeChanged(v8::RAILMode rail_mode) override;
@@ -720,6 +721,7 @@
   cc::BufferToTextureTargetMap buffer_to_texture_target_map_;
   bool are_image_decode_tasks_enabled_;
   bool is_threaded_animation_enabled_;
+  bool is_scroll_animator_enabled_;
 
   class PendingFrameCreate : public base::RefCounted<PendingFrameCreate> {
    public: